Lawrencium · element 103
The last actinide, whose outermost electron sits in a shell simple rules say it should not
Key facts
Lawrencium closes the actinide series. It is named after Ernest Lawrence, who invented the cyclotron, the machine that made most of the transuranium elements possible. It was first produced in 1961 at his laboratory, three years after his death.
For chemists the interesting thing about lawrencium is a single electron. Simple rules predict its outer electron should occupy a 6d orbital, as lutetium's does above it. Relativistic calculations say that in such a heavy atom the electron slips instead into a 7p orbital. In 2015 a measurement of the energy needed to remove that electron came in very low, just as the relativistic theory predicted.
Where it is found
Lawrencium is not found in nature and cannot be. Its longest-lived isotope, lawrencium-266, has a half-life of about 11 hours, and it was only identified in 2014 as a decay product in experiments making element 117. Most isotopes last seconds to minutes.
All lawrencium comes from accelerators. The usual route bombards a californium target with boron ions, or an americium target with oxygen-18, fusing the two nuclei together. The yields are a few atoms per hour of beam time. For chemistry experiments, physicists typically use lawrencium-256, which lasts about 27 seconds, and rely on fast automated systems to separate and detect it before it disappears.
How it was discovered
In 1961 Albert Ghiorso, Torbjorn Sikkeland, Almon Larsh and Robert Latimer at Berkeley's Heavy Ion Linear Accelerator bombarded a target of mixed californium isotopes with boron-10 and boron-11 ions. They observed alpha particles that they attributed to lawrencium-257, though later work suggested the isotope was probably lawrencium-258. The team proposed the name lawrencium and the symbol Lw.
In 1965 the Dubna group made lawrencium-256 by firing oxygen-18 at americium-243 and measured its decay more convincingly, leading to a long dispute. A joint IUPAC and IUPAP review in 1992 concluded that both laboratories deserved shared credit. The symbol had already been changed to Lr in 1963, and IUPAC confirmed the name lawrencium in 1997.
What we use it for
Lawrencium has no practical use and only a research role. Its science is about testing where the actinide series ends and what happens to chemistry when atoms become so heavy that their inner electrons move at a substantial fraction of light speed. In 1970 the first chemical experiment on lawrencium showed that it forms +3 ions in solution, like lutetium, confirming it behaves as a heavy group 3 metal rather than like nobelium next door.
The landmark result came in 2015 at the Japan Atomic Energy Agency in Tokai. Using an ion-source technique on atoms of lawrencium-256 arriving a few at a time, the team measured the first ionisation energy at just under five electronvolts, the lowest of any actinide and among the lowest of all elements. This matched predictions that the outer electron sits in a loosely held 7p orbital, and it reignited debate about whether lawrencium and lutetium belong in group 3 of the table.
Reading the numbers
Lawrencium's melting point of about 1,630 °C is a theoretical estimate, and no boiling point or density has been measured, because no visible sample has ever existed. The atomic mass of 266 is that of its most stable isotope. The configuration [Rn] 5f14 7s2 7p1 is the one predicted by relativistic quantum mechanics: the 5f shell is full, and the odd electron sits in 7p rather than 6d. That is why our data lists lawrencium in the d block and group 3 while giving it a first ionisation energy of about 470 kilojoules per mole, far below nobelium's 642. An electron in a 7p orbital is easier to remove than one in 6d. Despite this, lawrencium loses three electrons in chemical reactions and behaves like lutetium, because bonding involves all three outer electrons regardless of which orbitals they start in.
Safety and the environment
Lawrencium exists only as a handful of atoms in accelerator laboratories, decaying within minutes to hours. It has no environmental impact and presents no risk to the public. Laboratory hazards arise from the intense radioactivity of californium and americium targets and from the accelerator beam, both handled with heavy shielding and remote systems.
Did you know?
- Lawrencium's first ionisation energy was measured in 2015 using atoms produced a few at a time, one of the most delicate measurements in chemistry.
- Its longest-lived isotope, lawrencium-266, was found only in 2014, far down the decay chain of tennessine.
- The symbol was Lw for two years before IUPAC changed it to Lr in 1963.
- Ernest Lawrence won the 1939 Nobel Prize in Physics for inventing the cyclotron, and the Berkeley laboratory also carries his name.
- Lawrencium is the only actinide whose outermost electron is predicted to sit in a p orbital, a consequence of relativistic effects in a very heavy atom.
More in the actinides
The nearest neighbours of lawrencium in the family, by atomic number.
See all 15 actinides on one page, or browse all 118 elements.
Frequently asked questions
Is lawrencium an actinide or a transition metal?
It is conventionally the final actinide, but it also fits as the first member of the 6d transition series below lutetium. IUPAC discussions about group 3 have considered placing lutetium and lawrencium there.
What is lawrencium used for?
Nothing practical. It is made a few atoms at a time to test theories about the chemistry of extremely heavy elements.
Who discovered lawrencium?
Credit is shared between Albert Ghiorso's team at Berkeley in 1961 and Georgy Flerov's team at Dubna in 1965, following an IUPAC review in 1992.
How long does lawrencium last?
The most stable isotope has a half-life of around 11 hours. Those used in experiments typically survive for less than half a minute.
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Written by Anthony. Updated September 2026. Numerical data from Periodic-Table-JSON (CC BY-SA), cross-checked against the Lawrencium reference article. Spotted an error? Tell us.